Field emission display (FED) is a flat-panel display developed in recent years, and belongs to low-voltage cold cathode emission. This special emission characteristic endows FED with various superior properties which are different from those of the other flat-panel displays: low working voltage (200˜5000V), low power consumption, high brightness, low thickness, small size, light weight, good stability, long service life, fast response speed, full color display, no visual angel limitation, and good compatibility with the environment.
One of the key factors in preparing field emission devices with superior properties is the preparation of high performance fluorescent powder. The fluorescent materials currently used in field emission devices are mainly sulfide series, oxide series and oxysulfide series fluorescent powders which are used in traditional cathode-ray tubes and projection TV picture tubes. Sulfide series and oxysulfide series fluorescent powders have relatively high luminescent brightness and certain electric conductivity, but are liable to decompose under the bombardment of large beam electron beam to release elemental sulfur which “poisons” the pinpoint of the cathode, and produce other deposits which cover the surface of the fluorescent powders, reduce the fluorescent efficiency of the fluorescent powders, and shorten the service life of the field emission devices. The oxide fluorescent powders have good stability, but their luminescent efficiency is not high enough, and the materials are normally insulators. The performances of both materials still need to be improved.